\documentclass[12pt]{article}

\usepackage{amsmath}


\begin{document}

\begin{equation}
	f_{corr} = \begin{cases}
		1 - \epsilon \hspace{0.5mm} tan(\theta_{0}), & \text{if} \tan(\theta_{0}) < \epsilon^{-1} \\
		0, & \text{otherwise}
	\end{cases}
\end{equation}

\end{document}
